As used in this application and the appended claims, the word "drugs" is intended in its broadest sense to apply to all medicaments of any type, whether topical or systemic, applied for therapeutic purposes.
In recent years, there have been provided numerous bandages designed for delivery of drugs to the skin or mucosa of the wearer. One group of such prior bandages is represented by U.S. Pat. Nos. 3,632,740; 3,769,071; and 3,896,789, which teach the incorporation of specific active agents into a pressure sensitive adhesive for direct contact with skin lesions, and the like. Those bandages had no means for control of the rate of delivery and were objectionable for many applications because of the direct contact of the drug with the skin.
Another group of prior bandages employed specially designed diffusion membranes and drug reservoirs as represented by U.S. Pat. Nos. 3,598,122 and 4,069,307. Those bandages were complex, expensive, and involved difficult and precise manufacturing techniques.
An offshoot or refinement of the drug reservoir approach resulted in the micro-encapsulation of fine particles of the drug and the dispersion of the microcapsules within a matrix comprising a discrete layer of a laminar structure. Representative of such bandages are U.S. Pat. Nos. 3,996,934; and 3,598,123. Once again, such bandages were complex, costly and difficult to make.
U.S. Pat. No. 4,286,592 teaches another laminate bandage in which the drug is dispersed in a dissolution carrier matrix, and discusses the use of an adhesive to control the rate of dissolution and administration of the drug. Here, too, the bandage was complex and costly and required specific manufacturing parameters.
A simpler bandage is shown in U.S. Pat. No. 4,307,717, but it still required that the drug be dispersed in a matrix and it did not address the question of control of the rate of dissolution.